1. Field of the Invention
The present invention relates to a wafer, a method of manufacturing a package, and a piezoelectric oscillator.
2. Description of the Related Art
In recent years, a piezoelectric oscillator (in the form of a package) using crystal or the like as a time source, a timing source for a control signal or the like, or a reference signal source has been used in cellular phones and portable information terminal devices (see, for example, JP-A-2010-124015). Various piezoelectric oscillators of this type are known, and a piezoelectric oscillator of an SMD (Surface-Mounting Device) type is known as one example thereof. The piezoelectric oscillator of this type includes, for example, a base substrate and a lid substrate bonded together and made of a glass material, a cavity formed between the substrates, and a piezoelectric oscillating strip (electronic part) housed in the cavity with hermetical sealing.
For manufacturing the abovementioned piezoelectric oscillator, a plurality of recess portions for cavities are first formed in row and column directions over the entire wafer for lid substrate, and a piezoelectric oscillating strip is mounted on a wafer for base substrate in association with each of the cavities in the wafer for lid substrate. Then, the wafers are anodic-bonded with a bonding layer (metal film) interposed between them to provide a wafer bonded unit including a plurality of packages formed in the row and column directions on the wafer. The wafer bonded unit is cut for each of the packages (each of the cavities) formed in the wafer bonded unit to manufacture a plurality of piezoelectric oscillators having the piezoelectric oscillating strips enclosed in the cavities with hermetical sealing.